Building of a Hot Dry Rock Scientific Power Plant at Soultz-sous-Forets

摘要

The European geothermal research program for the extraction of energy from hot dry rocks started at Soultz-sous-Forets in 1987. The test site is located in France on the western edge of the Rhine Graben, some 50 km north of Strasbourg near the German border. The basement, granite, at Soultz lies beneath app. 1400 m of sedimentary rock; the fracture network in the granite has been explored down to 5000 m depth, where temperatures exceed 200 deg C. This scientific pilot plant will use a total of three boreholes of 5000 meters depth each, one injection well and two production wells. All three wells are drilled from the same platform. The wellheads are separated by not more than 6 m. Two out of the three wells are drilled directionally. Between 4500 m and 5000 m depth, the open hole sections of the bore holes have an horizontal spacing of around 600 m. It is expected that by end of 2005 this plant will be able to produce around 50 MW of thermal power at temperatures above 180 deg C. Up to 6 MW of electricity will be produced from this heat. The net output of the power plant is expected to be in the order of 4.5 MWe. The drilling of the 2nd production well GPK4 was finalized at the 11th of April in 2004. The well GPK4 reached a length of 5260 m and a vertical depth of 4982 m, the casing shoe of the floating 9 5/8"casing is at 4756 m measured depth (velence 4489 m True Vertical Depth), the open hole section was drilled in 8 1/2". An extensive suite of logs were acquired in the open hole section of GPK4. GPK4 was kicked off at 2100 m depth, the open hole section is separated app. 1150 m to the south from the wellhead. After the deepening of the 1st production well GPK2 in 1999, the stimulation of GPK2 in 2000, the drilling of the central injection well GPK3 in 2002, the stimulation of GPK3 in 2003 and the drilling of the 2nd production well GPK4 in spring 2004 the underground work of the scientific HDR pilot plant will be finalized with a stimulation of GPK4 and a re-stimulation of GPK3 in summer 2004.